Field of the Invention
The invention relates to an electronic device, and particularly relates to a power conversion apparatus and a protection method thereof while a feedback current signal of the power conversion apparatus is abnormal.
Description of Related Art
According to the related art, a power conversion apparatus is mainly used for converting an alternating current (AC) input voltage provided by a power company into a direct current (DC) output voltage suitable for use by different electronic devices. Thus, the power conversion apparatuses are widely used in computers, office automation devices, industrial control devices, communication devices, and other electronic apparatuses.
The conventional power conversion apparatus employs a current sensing pin of a pulse width modulation (PWM) control chip to sense the voltage at a common node between a power switch and a current sensing resistor and thereby adjusts the conduction state of the power switch accordingly, so as to protect the power conversion apparatus from overcurrent. However, when a short circuit occurs at the common node between the power switch and current sensing resistor, the PWM control chip is unable to detect the voltage at the common node between the power switch and the current sensing resistor, and thus the maximum duty cycle is applied to switch the power switch, which forces the power conversion apparatus to continuously output the abnormally large amount of current. As a result, the power conversion apparatus or internal components of the power conversion apparatus are more susceptible to damages.